Engine starter



Jan. 2, 1945. J. w. m GERALD 2,366,504

ENGINE STARTER Filed Jun 19, 1943 2 Sheets-Sheet l l4 0 I 4 3.]. 1s

Deceased By F 1% FJ'WH Execufrv'x Jam. 2, 1945.

J. w. FITZ GERALD ENGINE STARTER Filed- June 19. 1943 2 Sheets-She s: 2

Patented Jan. 2, 1945 T236 5 p ENGINE STARTER I John W. Fitz,; Gerald,deceased, late of Milwaukee,1 v Wis., by Mary- C, Fitz Gerald,executrix, Mil-,

waukee, Wis., 'assignorto Briggs &Stratton Corporation, Milwaukee, Wis.,a corporation of j This invention relates to engine starters of the socalled automatictype wherein thepinion' is automatically propelledto andfrom mesh with. the-ring gear of an engine to be started; a w

v A 'copending application Serial No. 491,513,

filed June 19, 1943, describes the advantages of using a-stack ofcupped-spring washers as the resilient driving connection through whichtorque is transmitted to the pinion of the starter."

The present invention employs the same type- 'ofresilient drivingconnection but has asits ob-' ject to so utilize the same that theapplication of the cranking load is cushioned solely by slippage in thedriving connection. As a result the cushioning of the starting load ismore easily controlled and predetermined as only one" factor:

namely slippage in the driving connection per se must be taken intoaccount. However, endwise resiliency is still retained to accommodatemisalignment of the pinionand ringgear duringthe meshing operation. 4

It is, therefore, a specifioobjeot of this inven tion to provide anengine starter wherein. the

resilient drivingconnection through which. torque is transmitted to thepinion consists of a slipping; disc coupling orclutch having endwiseresiliency inherent therein,

With the above and other objects in view which will appear as thedescription proceeds, this in-' vention resides in the novelconstruction, com, bination and arrangement of. parts substantiallyv ashereinafter described, and more particularly definedby the appendedclaims, it being understood that such changes in the precise embodisment of. the hereindisclosed invention may be madeas come within thescope of the claims.

The accompanying drawings illustrate two complete examples of thephysical. embodiment-of the invention constructed in accordance with thebest modes so far devised for the practical application of theprinciples thereof, and in which:

Figure 1 is a view in side elevation with parts thereof in section of anengine starter embodying this invention, said view showing the pinion inits normal retracted position; t

Figure 2 is a view similar to Figure 1 but showing the parts in thepositions they assume in the event of improper meshing, that is,end-to-end abutment of the pinion and ring gear teeth;

Figure 3 is a, view similar to Figure 1 showing the pinion fully meshed;

Figure 4 is a perspective view of a part of the pinion hub andillustrating the mannerin which the pinion stop in that form of theinvention S-O I E 1Applicationdune 2'19, 1943;1seiiariwb;491,514I

' 4Claims'.

(Chis- 7), 1 n a n, a r t Figure .5 is a view similar to Figure 1illustrating the application of this invention toa starter embodying theconventional type of. pinionstop.

Referring now more particularly to the accompanying drawings, in whichlike numerals indicate likeparts, the numeral 5 designates the shaft ofa, starter motor upon which the starter indicated generally by thenumeral'B is mounted.

The starter comprisesqa pinion Twmovable along 1 the shaft into and outof mesh withthe ring gear 8 o'f ian engine to'be started; and means foractuating and driving the pinion. 1 r i The pinion 1 has ahub 9internally threaded as at In to receive the threaded portion III ofanactuator l2.:,;Theractuator l2 consists of a tube the outer portion ofwhich has the external threads II and gtheinner portion of which has asmooth; cylindrical surface l3 of a diameter substantially equal to orat; leastnot, greater than the root diameter of its threaded portion, II. It

is freely slidable and rotatable on the motor shaft and is drivinglyconnectedv with the shaft through 5 This driving connection comprisesaflangel5 on the, actuator, a drivehead:,l-iifixed to the motor shaft,and a stack of alternately arranged cupped spring Washers l1 confinedbetween the,:

flange l5 andthe drive heads Ashell l 8 attached to the flange I5 andengagedover a flange on the drive head holds these parts againstseparation and-maintains the stack of spring washers under a degree ofcompression. l g

By virtue of the endwise pressure on the stack of cupped spring washersthey engage at their inner and, outer peripheral portions withsufiicient friction to provide for the initial transmission of torquefrom thedrive shaft to the actua tor to propelthe pinion to itsoperative driving position shown in Figure 3 and defined by a pinionstop indicated generally by" the numeral IS.

The pinion stop I9 contrary to customary practice is between the hub of;the pinion and the actuatorso that in picking up the cranking load :5;there isnoincrease of the endwise pressure on the stack of cupped springwashers. Consequently, the cushioning of the application of the crankingload to the starter is obtained solely by the frictionally resistedslippage between the spring washers of the driving connection;

However, in the event of tooth abutment as shown in Figure 2 the endwiseresiliency of the stack of spring washers provides the desired cushionand accommodates such misalignment.

shown in Figures 1, 2 and 3 is constructed; and The P n t I9 is f WW1 ad Si p e c nan impositive endwise, resilient driving connectionstruction. It consists of a slab 20 off the end of the pinion hubsecured back on the hub but in a position revolved several degrees fromits original position so that the teeth thereof are misaligned with theteeth of the hub. In this manner the teeth of the slab form abutmentsacross the ends of thespaces ofithe hub to; collide with; the ends ofthe teeth II on theactuator.

To hold the slab 20 in this position its outer peripheral portion isnotched to provide lug 22!? and spaces 22 and the end of the pinionhubis similarly notched to provide complementary lugs 2| and spaces 22;and a spring ring- 23 s'napped into a groove 24 on the lugs 21"" of thepinion-hub holds the slab assembled withthehub.

spaces therebetween; and means for securing the short length ofinternally threaded pinion hub to said end portion of the pinion hubwith its lugs in the notches of the pinionhub and with the threads ofsaid short length of pinion hub disaligned with the threads of thepinion hub portion so as; to provide; abutmentsr engageable with theends of the threads on the actuator.

3. In an engine starter having a pinion, an

actuator, a screw threaded connection between the" pinion and theactuator whereby relative rotation therebetween effects endwise movementof one with respect to the other to propel the pinion into andoutof meshwith the ring gear of an It is, of course, also possible to use theconventional form of pinion stop collar as shown in Figure 5. Here theactuator has a smooth. sunfaced extension 25 projecting throughthepinion.

and the stop collar 26 is secured on the outer end thereof in a positionto be engaged; by thexpinion when: fully meshed with ther-ing gean.

a From the foregoing: description taken in; con.-

. nection with the accompanying: drawings;. it will to moreaccuratelycontrol: the cushioning; efiecth What is claimed'as theinventionx is: I 1. In an engine starter: a pinion having: an.internally threadedhubportion; a pinion-actuator having a hub the outerend portion oiwhich.

is externally threaded and threadedly engaged? in the hub of the pinionand the inner portion. of which is smooth surfaced and of. a diameter:no greater than the root: diameter of its threadedi outer end portion:and a pinion stop for limiting:

endwise movement of the pinion outwardly oi the actuator comprising acollar having: internal. threads similar to those of the pinion hub and?fixed to the end of saidpinion-hub: in a position angularly onset withrespect- {id-the threads: thereof to provide al mtments across the ends:or the" spaces of the internal threads or the pinion hulo portion tocourse withthe add-scent ends of the threadson the actuator. g

2-. In an engine starter: a pinion-having. an in ternally threaded hubportion: a pinion actuator having a hub the outer end portion ofwhichis:externally threaded and threadedly engaged in the'hub of the pinion andan inner portion of which is smooth surfaced and of a diameterno reaterthan the root diameter of its threaded outer end portion; anda pinionstop for limiting endwise movement of thepinion outwardly of theactuator comprising arelatively short length of the internally threadedpinion hubhaving its outer periphery notched to provide lugs and spacestherebetween, the end portion of the pinion hub remote'from the pinion"being similarly notched to provide complementary lugs and- Deceased.

engine to be started, and having a driving head: an impositive endwiseresilient driving connection between the driving head and the actuator Icomprising, aplurality of cupped spring washers confined under a degreeof compression between the driving head and the actuator sufficient toestablish. an. initial. torque: transmitting connection: from: thedriving. head to: the: adlacent; washer and through the stack: of.-washersttoythea actuator solely' through. frictional. engagement; meansengaging one peripheral edge: ofxallr of the washers.- for holding; themaxially aligned, the: other peripheral edge; of all; of the: washersbeing; entirelyfree for: radial movement. in. or ..out...as-; endwisepressure onthe stack: 0t washers varies;

and a pinion. stop for" limitingyadvanceot the pinion so thatthe: torqueimpositively transmitted; .150": the: actuator by the, friction:between; adiw: cent spring washers is applied toithje pinion 4 In an.engine starterhaving a pinion. and a;

pinion actuator with. a :threaded connection-e.

th'erebetween' so: that. relative rotation of said; parts'eflfectstranslation of the pinion toward; amt.

from its operative driving positionrarr imposi tive endwise resilientdriving connection for. the

actuator: comprising, a driving; head. adapted to be fixed to. a powershaft to provide a: fixedldri e. ing: abutment, anabutment; on theactuator a plurality of. cupped: spring; washers assembled 911-;tern-ately in astack between said. abutments on.

-". the actuator anddriving..head;;1neans engaging;

endwise pressure so: asitol providegan'jendwise re silienttslipcoupling, operable through frictionzbea.

tween adjacent.- washcrsand. between. the end. washers and saidabutments; to eiiE-eotinitial torquertransmission. from; the drivingheadto; the

actuator; and a pinionrstopfor; l-im rtingradvance.

of the pinion so thatthe: torque impositiveld transmitted to theactuator by the: friction between. adjacent spring: washers isappliectpto "the; pinion.

MARY 0,. 'GIERALD Eaxecutrilr of the Estate of, John W. Fitz: Gemld.,

